A new study by the University of Minnesota Tourism Center examines family travel patterns when school starts before Labor Day.

Its researchers say it will provide data for policy makers mandating a school start date.

The study found family trips of two or more nights away decreased 50 percent in August or September when the start of school was before Labor Day. It also found family overnight travel from May to September decreased 30 percent when school opened before Labor Day.

Data for the study was drawn from the American Time Use Survey conducted by the U.S. Census Bureau.

The university says that while past studies have asked hypothetical questions about travel, the Tourism Center study examined actual travel behavior of families in five states — Minnesota, Michigan, Iowa, Wisconsin and Virginia.